Hours after being sworn in as President Trump’s attorney general, Pam Bondi declared to the entire Justice Department work force, “This shameful era ends today.”

That assertion, in one of 14 memos she issued on Wednesday, underscored what many current and former law enforcement officials describe as a major — and alarming — departure from years of Justice Department practice in which it steered clear of political rhetoric. The new tone, they said, suggests the opposite, seeming to promise a campaign of intimidation against career prosecutors and agents viewed as insufficiently loyal to Mr. Trump.

Such language is not unique to Ms. Bondi. Newly minted senior officials from powerful perches across the Justice Department have issued fiery broadsides against employees, denouncing “insubordination” or “abhorrent” conduct and, in one instance, vowing to pursue unspecified opponents of Mr. Trump’s cost-cutting efforts “to the ends of the Earth.”

One Justice Department lawyer who has worked in both Republican and Democratic administrations said the attorney general’s words were chilling in appearing to suggest that the new leadership of the department sees long-serving career lawyers as villains.

Another of Ms. Bondi’s memos urged “zealous” advocacy for the president’s agenda, part of a series of missives from top officials effectively demanding loyalty from their employees.

“I am not the president’s lawyer; I serve the people of the United States,” the lawyer said, speaking on the condition of anonymity for fear of retribution. “I’ve always been able to go to my supervisor and say, ‘I got this case and I’m uncomfortable with it.’ Based on the attorney general’s emails, it seems like those conversations are not welcome anymore, and that is scary.”